1. Field of the Invention
The present invention relates to an image processing apparatus for processing a image data or the encoded data thereof, and more sectionicularly to an image processing apparatus for compressing image data, expanding image encoded data, converting image data (scaling) and converting from the image encoded data to other code required in a facsimile or the like.
2. Description of the Related Art
Such kind of image processing apparatus is required in a facsimile, other image communication device, image filing system or the like.
An example of a conventional facsimile is shown in FIG. 2. In this facsimile, two kinds of coding/decoding device 201 and 203 are used for expansion of received encoded data or reduction of image data. The standardized MH, MR and MMR cording are executed by the coding/decoding device 201 as an encoding which is adapted to document image data. On the other hand, QM encoding which is arithmetic code conformed to ITU recommendation T.81, which is adapted to reduction of a halftone image, is executed by the coding/decoding device 203. A resolution conversion device 202 converts sizes of horizontal scanning and vertical scanning directions. These image processing apparatus are connected to data bus 210 and 211, and are placed under control of a host processor 206.
The host processor 206 selects the coding/decoding device 201 and 203 in accordance with capability of a receiving terminal to decode image data red in from a image input device 208. The encoded data is buffered by a code memory 205 to be transmitted from a communication device 207 like a modem to a communication line. The image is reconstituted by reverse processing thereof at receiving to be send to a image recorder/display device such as a printer.
In memory communication that transmission is carried out after once storing all the encoded data to be transmitted in the code memory 205, page size and encoding are required to be converted so as to adapt to capability of the receiving terminal (hereinafter referred to as code conversion). Typically, this code conversion function is realized as repetition of writing the image decoded at every one line in an image line memory 204, reading therefrom to perform resolution conversion processing, writing in an image line memory 204 again and reading out again to carry out encoding processing.
However, the conventional facsimiles are constituted by the structure that a plurality of image processing apparatus that various code conversion functions and resolution conversion functions are integrated into integrated circuits separately are connected to a common bus (an external bus) and the image memory placed on the external bus are shared. Therefore, the time required for read and write of large amount of image data and encoded data is increased, whereby there is the limitation in speeding up.